August 1, 2008 Supplemental Edition

Editors note: In its quest to provide the most up to date information on new silicone technology, the Silicone Spectator

endeav-ours to provide the latest information on new products and technologies. This information is provided as supplements to the quar-terly newsletters. The Silicone Spectator

welcomes articles from the public introducing new technologies of interest to those in the silicone community of practice. Andrew OLenick Editor August 1, 2008

This supplement to the Silicone Spectator is provided by Siltech LLC.

Multi Domain Silicone Waxes A New Class of Ingredients for Personal Care

Background

Dimethicone is difficult material to incorporate into many formulations since it is insoluble in both water and oil. Silicones lower surface tensions and provide elegant skin feel to many formulations when added to the oil phase. One of the most important physical attributes of a cosmetic product is skin feel. This attribute is a major consumer perceptible property of virtually all cos-metic products. Two major components in achieving good skin feel are cushion and play time. The ability to alter the cushion and play time in a cosmetic product is a highly prized formulation skill. If one rubs oil on the skin of the hand with the index finger, the Cushion is the gap between the finger and hand that the oil occupies. Play time is the length of time cushion exists. Many organic oils cushion and playtime are directly related. Materials with a lot of cushion have a lot of play time. Silicones added to formulations lower surface tension and provide elegant skin feel. The proper selection of alkyl silicone will allow for the ability to reduce play time without effecting cushion.

Alkyl Silicones Chemistry

Alkyl dimethicone polymers are a class of amphilic silicones that have both an alkyl (in RED) and a silicone portion (in Black) present in the same molecule. Mutually insoluble groups include water, oil, silicone and fluorocarbon.

CH3 CH3 CH3 CH3

| | | | CH3-Si-O- (- Si- O )a- (-Si-O )b - Si- CH3

| | | | CH3 CH3 CH2 CH3

| (CH2)20-CH3

Alkyl dimethicone compounds are made by the reaction of a silanic hydrogen containing polymer and an alpha olefin.

Alkyl silicones are insoluble in water, isopropanol, and dimethicone. They are soluble in mineral oil, triglycerides and fatty esters. Their solubility in oily materials makes these products of interest in personal care applications.

Despite the fact that alkyl silicones are soluble in many oils, they tend to aggregate at the surface, lowering surface tension. As the concentration of alkyl silicones is increased, the interface becomes saturated and micelles form. This is called the Criti-cal Micelle Concentration (CMC). It is this property of alkyl silicones that offer the formulator the most advantage. The lower-ing of surface tension from 30 dynes/cm2 to 20 dynes/cm2 makes the oil based product feel more like silicone.

The melt point of an alkyl dimethicone is determined in large part by the length of the alkyl group attached to the silicone. The amount of silicone can also effect the melt point, but to a lesser degree. The amount of silicone present on the molecule alters the hardness of the alkyl dimethicone. As the amount of silicone increases in a molecule, the material becomes softer.

The graphic below shows the action of amphilic materials in solution. In this case the multi domain silicones in oils. The bene-ficial effects of surface tension lowering on spreadability and both cushion and playtime are key benefits of this technology. The applicability reaches through all product types for personal care including serums, emulsions, sun products and pig-mented products.

States of Matter

A solid is a state of matter in which the material shows resistance to deformation and changes in volume. Solids have their molecules closely packed together in fixed positions. If the molecules are fixed in repeating groups a crystalline group occurs. A liquid is the state of matter in which molecules are fluid that is they can move easily around, assuming the shape of the container.

Alkyl dimethicone compounds have been around for many years. They are soluble in a variety of oils like mineral oil, and es-ters. The length of the alkyl chain determines the melt point of the traditional alkyl dimethicone. Consequently, cetyl (C16) dimethicone is liquid and Behenyl dimethicone (C22) is solid.

Unlike the products shown above, Multi-domain silicone polymers are carefully engineered materials that have segments called domains that have both solid and liquid alkyl groups placed on the same silicone backbone. The result is an inability to form a hard wax. The reason for this is that the molecule takes on the lowest energy confirmation in which there are solid domains and liquid domains within the matrix. The presence of these different domains within the polymer results in unique properties. The liquid and solid domains within the same molecule limit the ability to form hard solids and result in soft cosmetically ele-gant wax.

liquid domain (CH2)14-CH3

| CH3 CH3 CH3 CH2 CH3

| | | | | CH3-Si-O- (- Si- O )a- (-Si-O )b (O-Si-)c-O- Si- CH3

| | | | | CH3 CH3 CH2 CH3 CH3

| (CH2)20-CH3

solid domain

SILWAX

D221M

SILWAX

D221M is an example of a patent pending multi-domain alkyl silicone, having one solid and one liquid alkyl chains present on the same molecule. The result is a polymer that does not crystallize, rather orientates to provide a soft thixotropic material. The result is a cosmetically elegant product with wider melting point range of 34-37oC. Silwax D221M provides a very soft glossy feel on the skin. The product has been described as transient petrolatum, providing the feel and cushion of petrolatum, but has minimal playtime, rapidly disappears to leave high gloss and no tack, for this reason it has been called Vanishing Petrolatum.

A comparison of the multi-domain silicone polymer and product made by blending two silicone polymers on which there is one alkyl group each is shown below. The two products have the same average composition, but the multi-domain product is clearly different. This difference is because of the structuring provided by the multi domain design.

The comparison above clearly demonstrates that the effect of a multi domain alkyl silicone polymer. The product on the left is translucent, and flows slightly. The blended product is hard and opaque. The Multi domain silicone is thixotropic liq-uefying under pressure feels like petrolatum on the skin but has minimal playtime. It spreads rapidly and has no sticki-ness. This is attributed to the low surface tension and spreadability provided by the two domains in the one molecule.

This product represents only one of a large number of homologues available. The ability to alter the concentration of alkyl groups relative to each other, the amount of silicone in the molecule and the molecular weight allows for the custom tailor-ing of molecules for specific applications.

Comparison Multi-Domain alkyl silicone and blend of two different alkyl silicone polymers (having the same ratio of alkyl groups)

Add Phase C and mix until uniform. Maintain mixing and cool to 75oC and then pour into molds.

MOISTURIZING LIPSTICK

This moisturizing lipstick features excellent payoff, coverage, and barrier properties. The Silwax D-221M provides a elegant skin feel and improved spreadability because it reduces the surface tension on the skin.

1. Heat water to 75o C or higher. Add Polysurf with vigorous mixing and continue mixing until completely dispersed. 2. Allow to cool to 35o C while continuing to mix. 3. Add remaining Part A ingredients and mix until uniform. 4. Pre blend and mill Color Blend 5. Add part B and disperse in part A until uniform. 6. Heat part A to 60o C 7. Heat part C to 70oC and mix until all solids are dissolved 8. Add part D to part C, maintain temperature of combined phase at 65o C 9. Add Part AB to part CD with high speed propeller mixer. Cool to 30o C and fill

The Silwax D-221M provides an elegant skin feel and improved spreadability because it reduces the surface tension on the skin.

Silicone Spectator is electronic newsletters in the field of Silicone Chemistry, placed on the web four times a year. We welcome comments, articles and information on the content of this newsletter.

Siltech believes that the information in this supplement is an accurate description of the typical uses of the prod-uct. However, we disclaim any liability for incidental or consequential damages, which may result from the use of the product that are beyond its control. Therefore, it is the users responsibility to thoroughly test the product in their particular application to determine its performance, efficacy and safety. Nothing contained herein is to be considered as permission or a recommendation to infringe any patent or any other intellectual property right.